///
/// @file getopt-port.cpp
/// @brief getopt函数的多平台支持实现
/// @author zenglj (zenglj@live.com)
/// @version 1.0
/// @date 2024-11-21
///
/// @copyright Copyright (c) 2024
///
/// @par 修改日志:
/// <table>
/// <tr><th>Date       <th>Version <th>Author  <th>Description
/// <tr><td>2024-11-21 <td>1.0     <td>zenglj  <td>新做
/// </table>
///
#include "getopt-port.h"

#ifndef NEED_USUAL_GETOPT

#include <stdlib.h>
#include <string.h>

char * optarg;    /* argument associated with option */
int opterr = 1;   /* if error message should be printed */
int optind = 1;   /* index into parent argv vector */
int optopt = '?'; /* character checked for validity */

static void pass(const char * a)
{
    (void) a;
}
#define warnx(a, ...) pass(a)

#define PRINT_ERROR ((opterr) && (*options != ':'))

#define FLAG_PERMUTE 0x01  /* permute non-options to the end of argv */
#define FLAG_ALLARGS 0x02  /* treat non-options as args to option "-1" */
#define FLAG_LONGONLY 0x04 /* operate as getopt_long_only */

/* return values */
#define BADCH ((int) '?')
#define BADARG ((*options == ':') ? (int) ':' : (int) '?')
#define INORDER 1

#define EMSG ""

static char * place = EMSG; /* option letter processing */

/* XXX: set optreset to 1 rather than these two */
static int nonopt_start = -1; /* first non option argument (for permute) */
static int nonopt_end = -1;   /* first option after non options (for permute) */

/* Error messages */
static const char recargchar[] = "option requires an argument -- %c";
static const char recargstring[] = "option requires an argument -- %s";
static const char ambig[] = "ambiguous option -- %.*s";
static const char noarg[] = "option doesn't take an argument -- %.*s";
static const char illoptchar[] = "unknown option -- %c";
static const char illoptstring[] = "unknown option -- %s";

/*
 * Compute the greatest common divisor of a and b.
 */
static int gcd(int a, int b)
{
    int c;

    c = a % b;
    while (c != 0) {
        a = b;
        b = c;
        c = a % b;
    }

    return (b);
}

/*
 * Exchange the block from nonopt_start to nonopt_end with the block
 * from nonopt_end to opt_end (keeping the same order of arguments
 * in each block).
 */
static void permute_args(int panonopt_start, int panonopt_end, int opt_end, char ** nargv)
{
    int cstart, cyclelen, i, j, ncycle, nnonopts, nopts, pos;
    char * swap;

    /*
     * compute lengths of blocks and number and size of cycles
     */
    nnonopts = panonopt_end - panonopt_start;
    nopts = opt_end - panonopt_end;
    ncycle = gcd(nnonopts, nopts);
    cyclelen = (opt_end - panonopt_start) / ncycle;

    for (i = 0; i < ncycle; i++) {
        cstart = panonopt_end + i;
        pos = cstart;
        for (j = 0; j < cyclelen; j++) {
            if (pos >= panonopt_end)
                pos -= nnonopts;
            else
                pos += nopts;
            swap = nargv[pos];
            /* LINTED const cast */
            ((char **) nargv)[pos] = nargv[cstart];
            /* LINTED const cast */
            ((char **) nargv)[cstart] = swap;
        }
    }
}

/*
 * parse_long_options --
 *	Parse long options in argc/argv argument vector.
 * Returns -1 if short_too is set and the option does not match long_options.
 */
static int
parse_long_options(char ** nargv, const char * options, const struct option * long_options, int * idx, int short_too)
{
    const char * current_argv;
    char * has_equal;
    size_t current_argv_len;
    int i, match;

    current_argv = place;
    match = -1;

    optind++;

    has_equal = strchr((char *) current_argv, '=');
    if (has_equal != nullptr) {
        /* argument found (--option=arg) */
        current_argv_len = has_equal - current_argv;
        has_equal++;
    } else
        current_argv_len = strlen(current_argv);

    for (i = 0; long_options[i].name; i++) {
        /* find matching long option */
        if (0 != strncmp(current_argv, long_options[i].name, current_argv_len))
            continue;

        if (strlen(long_options[i].name) == current_argv_len) {
            /* exact match */
            match = i;
            break;
        }
        /*
         * If this is a known short option, don't allow
         * a partial match of a single character.
         */
        if (short_too && current_argv_len == 1)
            continue;

        if (match == -1) /* partial match */
            match = i;
        else {
            /* ambiguous abbreviation */
            if (PRINT_ERROR)
                warnx(ambig, (int) current_argv_len, current_argv);
            optopt = 0;
            return BADCH;
        }
    }
    if (match != -1) { /* option found */
        if (long_options[match].has_arg == no_argument && has_equal) {
            if (PRINT_ERROR)
                warnx(noarg, (int) current_argv_len, current_argv);
            /*
             * XXX: GNU sets optopt to val regardless of flag
             */
            if (long_options[match].flag == nullptr)
                optopt = long_options[match].val;
            else
                optopt = 0;
            return BADARG;
        }
        if (long_options[match].has_arg == required_argument || long_options[match].has_arg == optional_argument) {
            if (has_equal)
                optarg = has_equal;
            else if (long_options[match].has_arg == required_argument) {
                /*
                 * optional argument doesn't use next nargv
                 */
                optarg = nargv[optind++];
            }
        }
        if ((long_options[match].has_arg == required_argument) && (optarg == nullptr)) {
            /*
             * Missing argument; leading ':' indicates no error
             * should be generated.
             */
            if (PRINT_ERROR)
                warnx(recargstring, current_argv);
            /*
             * XXX: GNU sets optopt to val regardless of flag
             */
            if (long_options[match].flag == nullptr)
                optopt = long_options[match].val;
            else
                optopt = 0;
            --optind;
            return BADARG;
        }
    } else { /* unknown option */
        if (short_too) {
            --optind;
            return (-1);
        }
        if (PRINT_ERROR)
            warnx(illoptstring, current_argv);
        optopt = 0;
        return BADCH;
    }
    if (idx)
        *idx = match;
    if (long_options[match].flag) {
        *long_options[match].flag = long_options[match].val;
        return 0;
    } else
        return (long_options[match].val);
}

/*
 * getopt_internal --
 *	Parse argc/argv argument vector.  Called by user level routines.
 */
static int getopt_internal(int nargc,
                           char ** nargv,
                           const char * options,
                           const struct option * long_options,
                           int * idx,
                           int flags)
{
    char * oli; /* option letter list index */
    int optchar, short_too;
    static int posixly_correct = -1;
    size_t len;
    int optreset = 0;

    if (options == nullptr)
        return (-1);

    /*
     * Disable GNU extensions if POSIXLY_CORRECT is set or options
     * string begins with a '+'.
     */
    if (posixly_correct == -1) {
        errno_t err = _wgetenv_s(&len, nullptr, 0, L"POSIXLY_CORRECT");
        posixly_correct = (err == 0) && (len > 0);
    }
    if (!posixly_correct || *options == '+')
        flags &= ~FLAG_PERMUTE;
    else if (*options == '-')
        flags |= FLAG_ALLARGS;
    if (*options == '+' || *options == '-')
        options++;
    /*
     * reset if requested
     */
    if (optind == 0)
        optind = optreset = 1;

    optarg = nullptr;
    if (optreset)
        nonopt_start = nonopt_end = -1;
start:
    if (optreset || !*place) { /* update scanning pointer */
        optreset = 0;
        if (optind >= nargc) { /* end of argument vector */
            place = EMSG;
            if (nonopt_end != -1) {
                /* do permutation, if we have to */
                permute_args(nonopt_start, nonopt_end, optind, nargv);
                optind -= nonopt_end - nonopt_start;
            } else if (nonopt_start != -1) {
                /*
                 * If we skipped non-options, set optind
                 * to the first of them.
                 */
                optind = nonopt_start;
            }
            nonopt_start = nonopt_end = -1;
            return (-1);
        }
        place = nargv[optind];
        if (*place != '-' || (place[1] == '\0' && strchr(options, '-') == nullptr)) {
            place = EMSG; /* found non-option */
            if (flags & FLAG_ALLARGS) {
                /*
                 * GNU extension:
                 * return non-option as argument to option 1
                 */
                optarg = nargv[optind++];
                return INORDER;
            }
            if (!(flags & FLAG_PERMUTE)) {
                /*
                 * If no permutation wanted, stop parsing
                 * at first non-option.
                 */
                return (-1);
            }
            /* do permutation */
            if (nonopt_start == -1)
                nonopt_start = optind;
            else if (nonopt_end != -1) {
                permute_args(nonopt_start, nonopt_end, optind, nargv);
                nonopt_start = optind - (nonopt_end - nonopt_start);
                nonopt_end = -1;
            }
            optind++;
            /* process next argument */
            goto start;
        }
        if (nonopt_start != -1 && nonopt_end == -1)
            nonopt_end = optind;

        /*
         * If we have "-" do nothing, if "--" we are done.
         */
        if (place[1] != '\0' && *++place == '-' && place[1] == '\0') {
            optind++;
            place = EMSG;
            /*
             * We found an option (--), so if we skipped
             * non-options, we have to permute.
             */
            if (nonopt_end != -1) {
                permute_args(nonopt_start, nonopt_end, optind, nargv);
                optind -= nonopt_end - nonopt_start;
            }
            nonopt_start = nonopt_end = -1;
            return (-1);
        }
    }

    /*
     * Check long options if:
     *  1) we were passed some
     *  2) the arg is not just "-"
     *  3) either the arg starts with -- we are getopt_long_only()
     */
    if (long_options != nullptr && place != nargv[optind] && (*place == '-' || (flags & FLAG_LONGONLY))) {
        short_too = 0;
        if (*place == '-')
            place++; /* --foo long option */
        else if (*place != ':' && strchr(options, *place) != nullptr)
            short_too = 1; /* could be short option too */

        optchar = parse_long_options(nargv, options, long_options, idx, short_too);
        if (optchar != -1) {
            place = EMSG;
            return optchar;
        }
    }

    optchar = (int) *place++;
    oli = strchr((char *) options, optchar);
    if (optchar == (int) ':' || (optchar == (int) '-' && *place != '\0') || oli == nullptr) {
        /*
         * If the user specified "-" and  '-' isn't listed in
         * options, return -1 (non-option) as per POSIX.
         * Otherwise, it is an unknown option character (or ':').
         */
        if (optchar == (int) '-' && *place == '\0')
            return (-1);
        if (!*place)
            ++optind;
        if (PRINT_ERROR)
            warnx(illoptchar, optchar);
        optopt = optchar;
        return BADCH;
    }
    if (long_options != nullptr && optchar == 'W' && oli[1] == ';') {
        /* -W long-option */
        if (*place)
            ;
        else if (++optind >= nargc) { /* no arg */
            place = EMSG;
            if (PRINT_ERROR)
                warnx(recargchar, optchar);
            optopt = optchar;
            return BADARG;
        } /* white space */
        place = nargv[optind];
        optchar = parse_long_options(nargv, options, long_options, idx, 0);
        place = EMSG;
        return optchar;
    }
    if (*++oli != ':') { /* doesn't take argument */
        if (!*place)
            ++optind;
    } else { /* takes (optional) argument */
        optarg = nullptr;
        if (*place) /* no white space */
            optarg = place;
        else if (oli[1] != ':') {    /* arg not optional */
            if (++optind >= nargc) { /* no arg */
                place = EMSG;
                if (PRINT_ERROR)
                    warnx(recargchar, optchar);
                optopt = optchar;
                return BADARG;
            }
            optarg = nargv[optind];
        }
        place = EMSG;
        ++optind;
    }
    /* dump back option letter */
    return optchar;
}

/*
 * getopt --
 *	Parse argc/argv argument vector.
 */
int getopt(int nargc, char * nargv[], const char * options)
{
    return getopt_internal(nargc, nargv, options, nullptr, nullptr, FLAG_PERMUTE);
}

/*
 * getopt_long --
 *	Parse argc/argv argument vector.
 */
int getopt_long(int nargc, char * nargv[], const char * options, const struct option * long_options, int * idx)
{

    return (getopt_internal(nargc, nargv, options, long_options, idx, FLAG_PERMUTE));
}

/*
 * getopt_long_only --
 *	Parse argc/argv argument vector.
 */
int getopt_long_only(int nargc, char * nargv[], const char * options, const struct option * long_options, int * idx)
{

    return (getopt_internal(nargc, nargv, options, long_options, idx, FLAG_PERMUTE | FLAG_LONGONLY));
}

#endif /* NEED_USUAL_GETOPT */
